/*******************************************************************************
 * Copyright (c) 2004, 2005 Elias Volanakis and others.
�* All rights reserved. This program and the accompanying materials
�* are made available under the terms of the Eclipse Public License v1.0
�* which accompanies this distribution, and is available at
�* http://www.eclipse.org/legal/epl-v10.html
�*
�* Contributors:
�*����Elias Volanakis - initial API and implementation
�*******************************************************************************/
package eu.hydrologis.jgrass.formeditor.parts;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.List;

import org.eclipse.gef.EditPart;
import org.eclipse.gef.EditPolicy;
import org.eclipse.gef.RootEditPart;
import org.eclipse.gef.editparts.AbstractTreeEditPart;
import org.eclipse.gef.editpolicies.RootComponentEditPolicy;

import eu.hydrologis.jgrass.formeditor.model.AModelElement;
import eu.hydrologis.jgrass.formeditor.model.WidgetsDiagram;

/**
 * TreeEditPart for a ShapesDiagram instance.
 * This is used in the Outline View of the ShapesEditor.
 * <p>This edit part must implement the PropertyChangeListener interface, 
 * so it can be notified of property changes in the corresponding model element.
 * </p>
 * 
 * @author Elias Volanakis
 */
public class WidgetDiagramTreeEditPart extends AbstractTreeEditPart implements PropertyChangeListener {

    /** 
     * Create a new instance of this edit part using the given model element.
     * @param model a non-null ShapesDiagram instance
     */
    WidgetDiagramTreeEditPart( WidgetsDiagram model ) {
        super(model);
    }

    /**
     * Upon activation, attach to the model element as a property change listener.
     */
    public void activate() {
        if (!isActive()) {
            super.activate();
            ((AModelElement) getModel()).addPropertyChangeListener(this);
        }
    }

    /* (non-Javadoc)
     * @see org.eclipse.gef.examples.shapes.parts.ShapeTreeEditPart#createEditPolicies()
     */
    protected void createEditPolicies() {
        // If this editpart is the root content of the viewer, then disallow removal
        if (getParent() instanceof RootEditPart) {
            installEditPolicy(EditPolicy.COMPONENT_ROLE, new RootComponentEditPolicy());
        }
    }

    /**
     * Upon deactivation, detach from the model element as a property change listener.
     */
    public void deactivate() {
        if (isActive()) {
            super.deactivate();
            ((AModelElement) getModel()).removePropertyChangeListener(this);
        }
    }

    private WidgetsDiagram getCastedModel() {
        return (WidgetsDiagram) getModel();
    }

    /**
     * Convenience method that returns the EditPart corresponding to a given child.
     * @param child a model element instance
     * @return the corresponding EditPart or null
     */
    private EditPart getEditPartForChild( Object child ) {
        return (EditPart) getViewer().getEditPartRegistry().get(child);
    }

    /* (non-Javadoc)
     * @see org.eclipse.gef.editparts.AbstractEditPart#getModelChildren()
     */
    protected List getModelChildren() {
        return getCastedModel().getChildren(); // a list of shapes
    }

    /* (non-Javadoc)
    * @see java.beans.PropertyChangeListener#propertyChange(java.beans.PropertyChangeEvent)
    */
    public void propertyChange( PropertyChangeEvent evt ) {
        String prop = evt.getPropertyName();
        if (WidgetsDiagram.CHILD_ADDED_PROP.equals(prop)) {
            // add a child to this edit part
            // causes an additional entry to appear in the tree of the outline view
            addChild(createChild(evt.getNewValue()), -1);
        } else if (WidgetsDiagram.CHILD_REMOVED_PROP.equals(prop)) {
            // remove a child from this edit part
            // causes the corresponding edit part to disappear from the tree in the outline view
            removeChild(getEditPartForChild(evt.getNewValue()));
        } else {
            refreshVisuals();
        }
    }
}
